Structural, AC conductivity, impedance and dielectric study of nanocrystalline MFe2O4 (M = Mg, Co or Cu) spinel ferrites

Nanocrystalline MFe2O4 (M = Mg, Co or Cu) spinel ferrites were prepared using novel combustion method and its structural, AC conductivity, impedance and dielectric properties were investigated. The powder X-ray diffraction analysis shows that the size and lattice constant of nanocrystalline MgFe2O4, CoFe2O4 and CuFe2O4 are 10.4, 28.6 and 9.6 nm (8.330, 8.369, and 8.342 angstrom ), respectively. Further the Raman spectra confirm the spinel phase formation and five active Raman modes such as 1A(1g), 1E(g), 3T(2g) are assigned for each ferrite. The Fourier transform infrared spectra confirms the formation of tetrahedral and octahedral sites. The electrical properties such as AC conductivity, impedance, dielectric constant and tan delta are reported. The value of AC conductivity at 30 degrees C (at 1 Hz) is 1.12 x 10(-8), 1.91 x 10(-10) and 9.19 x 10(-8) S/cm, respectively for MgFe2O4, CoFe2O4 and CuFe2O4 ferrites. The activation energy of AC conductivity process, calculated using Arrhenius relation is ranged from 0.45 to 0.56 eV. The impedance analysis shows that the contribution of grain boundary is more than that of grain for the electrical behavior of the prepared samples. The dielectric study shows that the CoFe2O4 has the lowest value of dielectric constant and tan delta among the three investigated samples.